By far the easiest method  of metal preparation is sand or media blasting for two major reasons. The first is that a sand/media blasted part, once cleaned with a metal prep solution to remove all dust and oils from the surface stripped surface, leaves the metal sufficiently "roughed-up" enough to give the primer a good surface on which to "stick". The second major advantage is time. It takes far less time to sand-blast a part and clean it, than any of the other methods. You simply blast the part, clean it of any debris and prime it. Pretty simple process. It all depends on whether you have the equipment to do this task

Mechanical stripping can be performed in any number of ways using power tools to remove the paint. My preferred method is to use a hand-held grinder with a wire wheel attached. I frequently also use wire brushes, sanding disks, and scrapers, depending on the parts shape and size.

The wire wheel though, allows me to remove rust and paint in one quick step and will remove all coatings to the bare metal. One word of caution though. Using a wire wheel to remove paint and rust does not adequately remove the rust from the metals surface. If you were to paint over the top of the wire wheeled metal without any further rust abatement, it is going to rust again in the future. In order to properly prepare the metal for painting all traces of surface rust must be completely removed or neutralized before primer is applied.